Problem

Google Apps GSync keeps spinning and not connecting

Steps to reproduce

1. Connect to Google Apps GSync
2. The spinning wheels keeps spinning and the 'Start syncing users' button is never clickable.
3. Check the Console Tools and you'll see Error 500

Expected

Successfully connected to Google Apps

Cause

The domain list is failing to load and JIRA has nothing to do with this. It is happened when JIRA has a valid token that Google allow us into but isn't allowed to read domains. Basically JIRA would ask Google for all the relevant permissions, including the permission to read the domain list but then this failure means Google said we can't. 

In another word it happens when JIRA and Google Apps is connected, JIRA would ask Google to make sure that the Google Apps admin performing the connection has permission to perform all the stuff, but when JIRA actually try to do that task on their behalf, it turns out that they're not allowed to.

Workaround

Give some extra permissions to the Google Apps admin.